Luminescent Dimeric Oxalate-Bridged Eu/Tb-Implanted Arsenotungstates: Tunable Emission, Energy Transfer, and Detection of Ba Ion in Aqueous Solution.

Two cases of lanthanide (Ln)-implanted arsenotungstates, KNaH[{(AsWO(HO))Ln(HO)}(CO)]·87HO (Ln = Eu (), Ln = Tb ()) and their codoped derivatives EuTb-POM ( = 0.01 (), = 0.04 (), = 0.1 (), = 0.2 ()) were prepared and further characterized by powder X-ray diffraction, infrared spectra, and thermogravimetric analyses. An X-ray structural analysis of and indicates that they both present a dimeric oxalate-bridged Ln-implanted lanthanide arsenotungstate polyanion structure. Under the O → W LMCT excitation at 265 nm of arsenotungstate polyanions, the emissions of Ln ions in and are sensitized and the lifetimes are prolonged. Codoped compounds - demonstrate a color-tunable emission from green to red by adjusting the Eu/Tb ratio. Emission spectra and time-resolved emission spectroscopic studies were performed for to further authenticate the energy transfer processes from excited arsenotungstates to the Eu and Tb metal ions and also between the Eu and Tb centers. More interestingly, is an effective fluorescent probe for the recognition and detection of Ba ions in aqueous solution. The optical properties of the Ln-implanted arsenotungstate compounds not only expressly reveal distinctive energy transfer processes in those compounds but also broaden the application of POM-based materials in the fluorescence sensing field.